Ultrasound elasticity imaging (UEI) has held great promise for diagnosing breast cancer. However, one of the big problems for UEI has been the requirement of continuous, focussed deformations over previously defined lesions. This has religated the technique to a purely diagnostic role, which requires significant physician interaction. In this proposal, we intend to preliminarily test two possible methods for converting USI into a true screening tool for diagnosing breast cancer. This will be done by combining elasticity imaging with a previously funded, novel combined x-ray mammography/3D ultrasound device now being developed by the University of Michigan and GE Medical. In this device, acquired ultrasound images are perfectly aligned with x-ray mammograms. The unique implementation will be that UEIs will be acquired by estimating the strain in deformations of the breast at only 2 or 3 discrete compressions using the calibrated compression paddle in the x-ray mamniography/3D ultrasound device. Strain estimates between these discrete positions will be accomplished by determining the 3D non-linear warps between the separate ultrasound images at different deformations with the local derivatives defining the strain. The warping estimates will be performed using a University of Michigan developed mutual information technique, MIAMI fuse. In addition, we will also test discrete 3D speckle tracking as an alternative method. These methods will be compared quantiatively to continuous 3D speckle tracking as a gold standard in simulations, phantoms, and in a limited way in a small group of patients. In addition to strain estimates, a method will be tested to see if Young's modulus estimates of breast masses can be made given the unique additional information provided by the perfectly matched x-ray mammograms. The x-ray images will define a fat boundary around nodules that permits the Young's modulus calculation from the matched ultrasound strain estimates. Success could lead to a unique ultrasound-based imaging mode for breast cancer screening.